This invention relates to a system and method for feeding fuel to a fluidized bed furnace and more particularly to such a system and method utilizing a pneumatic transport for low grade fuels having high water content and substantial adhesive properties.
The use of pneumatic transports for fluidized beds is generally known. For example, Whelan, U.S. Pat. No. 3,484,948, discloses a pneumatic transport for particulate material including an apparatus for exchanging heat between a gas and the particulate matter. However, the use of pneumatic transports in a fuel feed system for low grade industrial and municipal waste fuels in the form of paste or slurry present several distinct problems. For example, waste fuels often have significant adhesive properties that are associated with their relatively high water content. Also, waste fuels have a low heating value, as well as a high concentration of salts. Further, the quality and characteristics of waste fuels can vary considerably over time. Consequently, feeding of these fuels to a furnace for incineration is difficult, and improper feed systems can result in unstable furnace combustion, high pollutant emission, furnace slagging, and the formation of agglomerations within both the feed system and furnace.